Benzodiazepines (BZs) are prescribed widely for the treatment of anxiety and sleep disorders. Although BZs are considered to be among the safest prescription drugs in modern medicine, their utility is constrained by a number of side effects, including the liability for abuse and dependence, and recent epidemiological research suggests BZ abuse is on the rise in the U.S. The overall goal of this application is to investigate the extent to which GABAA receptor subtypes are differentially involved in the anxiolytic effects, self-administration, and physical dependence associated with BZ ligands, using relevant nonhuman primate models. Ligands with selectivity for different BZ-sensitive receptors (i.e., 11GABAA, 12GABAA, 13GABAA, and 15GABAA subtypes) will be used as pharmacological probes to determine the role of these receptors in the behavioral effects of BZs. Anxiolytic activity will be evaluated in rhesus monkeys using conflict procedures in which food- maintained behavior is concurrently suppressed by response-produced presentations of an aversive stimulus. Reinforcing effects will be evaluated using progressive-ratio schedules of i.v. drug self-administration. Physical dependence and tolerance following chronic BZ treatment will be measured using quantitative observation techniques. For all procedures, systematic antagonism studies will be used to dissociate effects due to specific GABAA receptor subtypes. Identification of compounds that are effective anxiolytics lacking abuse and dependence potential in our studies will provide fundamental information for developing safer and more broadly effective anti-anxiety medications, as well as compounds that may be beneficial in the pharmacological management of BZ dependence.